The present invention relates to a rotary piston compressor, and more specifically to a Root's type compressor.
Rotary piston compressors of the foregoing type include a housing with a suction connection and a pressure connection formed on the housing and two pistons positioned in the housing and rotated by a drive gear in the opposite directions. In such compressors the lemniscate-shaped pistons uniformly rotate in opposite directions. A gaseous conveying agent flows into the housing enclosing the pistons, through the suction connection and is forcibly conveyed in the chambers, formed by the housing and the pistons, to the pressure connection. When the head of each piston appears at the edge of the pressure connection the conveyed gas volumes become compressed by a return flow from the pressure connection. A compression pressure is adjusted in accordance with the resistance of the tubular conduits and the equipment connected to the compressor.
In conventional rotary piston compressors, the housing is formed of three portions which are a cylindrical intermediate portion and two side portions formed as covers closing the end faces of the intermediate portion. The intermediate portion accommodates the pistons. The suction connection and the pressure connection are formed radially at the center of the cylindrical intermediate portion. The drive shafts which rotate the pistons are supported in side housing portions by two-row taper ball bearings which are sealed in the compressor housing by slide ring sealings. The control drive gear formed of two meshing gears is accommodated in one of the housing side portions while one of the shafts extends through the other side portion outwardly to be connected to a drive.
The structure of the housing of the known compressor of the type under discussion is not very favorable in manufacture. Firstly it is not satisfactory because three parts of the housing must be manufactured precisely. Secondly, since the suction connection and the pressure connection must be positioned one against the other centrally on the cylindrical intermediate portion, a divided core mold must be provided for die cast manufacturing of the intermediate portion, which normally makes the use of the die cast machine quite expensive. Moreover, two-row taper ball bearings and slide ring sealings make the manufacture of such a compressor more costly. The producing of the components of cast iron results in a relatively heavy rotary piston compressor.